This invention relates to a composite material useful as a chemical mat film and a photosensitive film.
There is a known chemical mat film which comprises a transparent plastic film, and a chemical mat layer containing a binder and finely divided solid particles. Because of the presence of the fine particles, the surface of the chemical mat layer is slightly roughened. As a result, the chemical mat film is writable with a pencil or a ball-point pen and permits a coating such as a photosensitive coating to be provided thereon. Thus, such a chemical mat is widely utilized in many applications, for example, as tracing films for drawing and as substrates for photosensitive films to be used for the preparation of maps, etc. In such a case, the photosensitive film is subjected to image exposure and then developed to form a resin image. The resin image is thereafter colored with a dye.
When used as a substrate of photosensitive films, however, known chemical mat films pose a problem that not only the resin image to be colored but also the chemical mat layer is colored or stained during the formation of the colored image. To cope with this problem, there is proposed a method wherein a thermosetting or a UV-curable resin is incorporated into the chemical mat layer. In this case, the resin should be completely cured by heating or by irradiation of UV rays prior to the coloring step and, thus, this method is not economically advantageous. In addition, the curing often causes curls of the film. As an alternative method for solving the problem of coloring of the chemical mat layer, a specific composition for the chemical mat layer may be used. However, there have been no successful compositions capable of providing a stainless chemical mat layer.